The interior of kilns used to manufacture cement is lined with refractory materials that can withstand high working temperatures, which can reach around 1500 degrees Celsius in some areas, and the resulting physical and chemical reactions. Various refractory materials can be used but they all present drawbacks operationally and functionally, particularly with regard to progressive deformation by high kiln temperatures, spalling and cracking.
Known refractory materials currently in use are made up of glass-manufacture crucibles, lime, silica, chromium, magnetite, aluminum oxide and aluminous silica glass (Norton, Refractarios, first Spanish edition published by Blume in 1972). Japanese Patent no. JP11230679 describes variations in the porosity of refractory bricks, whereas JP 11130485 describes refractory materials as prefabricated panels, JP11201649 describes refractory materials with glass textures, European Patent no. EP0911594 teaches the arrangement of refractory materials, whereas German Patent DE19729582 discloses prefabricated bricks. In general, the above inventions are designed for the steel industry, and the resulting chemical composition or form are either not applicable to the peculiarities of the cement industry or are not detailed and sufficiently established.
U.S. Pat. No. 5,030,595 describes a carbon bake refractories of an unfired brick, which is useful for aluminum metal production. The silicon carbide content is limited to a maximum of 20% by weight, and high proportions of clays, alumina aggregates, and carbon are added. This unfired brick would be particularly unsuitable for cement kilns. In cement kilns it is necessary to use a greater amount of silicon carbide to avoid the carbon component.
Therefore, different compositions or bricks of refractory materials have different degrees of hardness and resistance to the deformation caused by differences in kiln temperature in different parts of the same kiln. Consequently, there is a need to find a refractory material of greater hardness and resistance than the materials currently employed. In the present invention this technical problem is solved and the resulting material described herein is suitable for uses in cement kilns.